This research program has the dual goal of investigating the mechanism of interocular suppression in strabismus and studying eye-hand coordination before and after surgery for strabismus. During years one and two, it has been found that training for the task of controlling velocity of a visual target involves changes in oculomotor, as well as visual-motor responses. Interocular suppression in strabismus, studied in the paradigm of dichoptic masking, was shown to occur even in absence of good spatial continguity and over a greater range of stimulus onset asynchrony than in normal binocular vision, but only when the masking stimulus is given to the normally fixing eye while the test stimulus is presented to the squinting eye. During year three of this program, latency differences between the normally fixing eye and the squinting eye will be studied directly and in the same patients before and after surgery for strabismus. Also, sensitivity to particular stimuli will be investigated across the retina, in the normal and the amblyopic eye, to link differences in visual latency to differences in other relevant sensory responses, in an attempt to find a common basis for several major impairments of the mechanism of binocular vision in strabismus.